Field of the Disclosure
Aspects of the present disclosure generally relate to an imaging apparatus and a control method therefor.
Description of the Related Art
Concurrently performing capturing of a moving image and a still image enables, during playback, not only viewing a captured scene as a moving image, but also enjoying a crucial scene in the moving image as a still image. Generally, if the moving image played back provides a riffling feeling in a sort of frame-by-frame playback manner, the high quality of the moving image would be greatly lost. To prevent the occurrence of such a riffling feeling, it may sometimes be necessary to set an accumulation time close to one frame period in a series of image capturing operations. In other words, if the frame rate is 30 frames per second (fps), a relative long exposure time such as 1/30 seconds or 1/60 seconds is adequate. On the other hand, with regard to a still image, since a sharpness as sharp as a stopped image captured in an instant is desired, to achieve a stop motion effect, it sometimes may be necessary to set a short exposure time, such as about 1/1000 seconds.
Heretofore, proposed imaging apparatuses, each of which concurrently captures both a moving image and a still image as two video images, include an imaging apparatus which is equipped with two image sensors, including an image sensor for moving images and an image sensor for still images, and an imaging apparatus in which an image sensor is provided with different photoelectric conversion portions that are respectively used for moving images and still images.
Japanese Patent Application Laid-Open No. 2010-157893 discusses a technique to vary conditions, such as an exposure time and an exposure amount, at high speed and in a free manner by transferring electric charges obtained by conversion by a photoelectric conversion portion to an accumulation portion a plurality of times and collectively accumulating the electric charges transferred a plurality of times. Therefore, the technique discussed in Japanese Patent Application Laid-Open No. 2010-157893 can be applied to conceiving an imaging apparatus in which each pixel is provided with two signal retention portions respectively used for accumulating electric charges for moving images and still images. Specifically, in one frame period, the imaging apparatus evenly disperses short accumulation periods in one frame period and performs accumulation a plurality of times at the signal retention portion for moving images, thus acquiring a moving image. Then, the imaging apparatus performs accumulation at the signal retention portion for still images with use of a time between the short accumulation periods for moving images, thus acquiring a still image.